Low Back Pain¶
Chapter 18 | Part 2: Cardinal Manifestations and Presentation of Diseases
KEY CLINICAL POINTS¶
- Low back pain (LBP) is the leading cause of years lived with disability worldwide, with all-cause medical costs exceeding $300 billion/year in the United States
- Pain categorization into nociceptive, neuropathic, and nociplastic types is essential for guiding treatment decisions
- 80% of patients with acute nonradicular LBP still experience pain at 1 month; most chronic LBP patients show minimal improvement after 6 months
- Red flags must be identified to rule out serious pathology (cauda equina syndrome, infection, malignancy, fracture)
- Multimodal treatment prioritizing nonpharmacologic therapies (physical therapy, exercise, cognitive-behavioral therapy) with graded addition of pharmacologic and interventional treatments is recommended
1. DEFINITION & OVERVIEW¶
Low back pain (LBP) encompasses pain localized to the lumbar region, with or without radiation to the lower extremities. It can be classified by duration (acute <3 months vs chronic ≥ 3 months), by pain mechanism (nociceptive, neuropathic, nociplastic, or mixed), and by anatomic source (mechanical/axial vs radicular). Understanding pain categorization is critical as it predicates treatment decisions at all levels of care.
Table 18-1: Distinguishing Characteristics of Nociceptive, Neuropathic, and Nociplastic Low Back Pain¶
| Clinical Characteristic | Nociceptive Pain | Neuropathic Pain | Nociplastic Pain |
|---|---|---|---|
| Etiology | Cumulative stress | Usually preceded by spine degeneration; herniated disk may occur after inciting event | Usually insidious, sometimes after physically or psychologically traumatic event |
| Onset | Insidious | Usually insidious | Usually insidious |
| Examples/Causes | Degenerative spondylosis, myofascial pain | Herniated disk, spinal stenosis | Nonspecific back pain; may present as mechanical or radicular pain |
| Descriptors | Aching, deep, throbbing | Sharp, shooting, lancinating | Similar to neuropathic descriptors, may include nociceptive ones |
| Sensory Deficits | Uncommon | Common | Occur sometimes, often outside dermatomal distribution |
| Clinical Characteristic | Nociceptive Pain | Neuropathic Pain | Nociplastic Pain |
|---|---|---|---|
| Motor Deficits | May be pain-induced | Frequent | Pain-induced weakness, fatigue common |
| Hypersensitivity | Occasionally, with myofascial pain | Common | Extremely common |
| Pain Pattern | May be referred into leg (usually proximally) in nondermatomal distribution | Reflects dermatomal pattern | Diffuse, often outside anatomic pain patterns |
| Precipitating/Relieving Factors | Worse with activities that stress structure | More unpredictable; spinal stenosis may be alleviated by forward flexion | Unpredictable, typically worse with stress |
| Autonomic Signs | Uncommon | Present in up to 25% of patients | Sympathetic hyperactivity and POTS very common |
| Accompanying Symptoms | Co-existing psychopathology common, increased rate of neck pain | Higher levels of psychological stress and QoL decrements | Very high levels of psychological distress and sleep abnormalities; co-prevalent with other nociplastic conditions |
| Diagnosis | Imaging correlated with history/PE and diagnostic blocks | History and neurologic exam; s-LANSS and painDETECT instruments | History, physical exam (diffuse tenderness), central sensitization inventory, conditioned pain modulation |
1.1 Pain Categories¶
Three major categories of pain exist: Nociceptive Pain: The most common form of chronic LBP; results from activity in neural pathways secondary to actual or potentially tissue-damaging stimuli. Typically worsens with activities that stress responsible structures, usually secondary to degenerative changes, and tends to be progressive. Referral patterns are more variable and proximal than radicular pain, not following dermatomal distribution. Neuropathic Pain: Caused by injury or disease affecting the somatosensory nervous system. Often accompanied by paresthesias, numbness, and sometimes allodynia. More unpredictable with wide fluctuations and paroxysms, often presents with focal neurologic findings. Radiculopathy can occur without pain, and radicular pain frequently occurs without neurologic deficits. Nociplastic Pain: Pain that develops due to abnormal processing of pain signals without evidence of tissue damage or somatosensory system pathology (central sensitization). Also termed "nonspecific LBP." Characterized by diffuse pain, superficial tenderness, and pain patterns deviating from normal neuroanatomy. Patients may experience pain-induced weakness, multiple concomitant pain conditions, and sensory deficits outside classic dermatomal maps.
1.2 Mixed Pain Phenotypes¶
Studies in orthopedic populations suggest over half of individuals may have mixed pain phenotypes. Different pain categories may occur simultaneously. For example: - Herniated disks and spinal stenosis can result in concomitant nociceptive pain - Individuals with central sensitization often experience neuropathic and nociceptive pain at lower thresholds - More than one-third (range <10-55%) of chronic LBP patients report neuropathic qualities - 10-20% of the overall back pain population has nociplastic pain
2. EPIDEMIOLOGY¶
Low back pain is among the leading causes of years lived with disability worldwide and the principal cause of work-related disability in nearly all industrialized countries.
2.1 Prevalence and Economic Impact¶
- 28-34% of Americans experienced LBP in the past 3 months - LBP accounts for >57 million unique patient visits annually - All-cause medical costs in the United States exceed $300 billion per year
2.2 Risk Factors for Chronic LBP¶
- Female sex - African-American race - Older age - Unemployment - Obesity - Sedentary lifestyle
2.3 Condition-Specific Epidemiology¶
Herniated Disk: - Annual incidence of symptomatic lumbar disk herniation: ~1% - Point prevalence: 1.5-4% - Prevalence of asymptomatic disk herniation: 29-43% (increases with age) - 38-56% of symptomatic individuals report an inciting event (falls, lifting, motor vehicle collisions most common) Spinal Stenosis: - Affects approximately 11% of the U.S. population - Prevalence dramatically increases with age - Most common levels: L4-5 (92%) and L3-4 (66%) - Most people have multiple nerve root involvement Facet Joint Pain: - Affects approximately 10-15% of individuals with axial LBP - Prevalence increases with age Sacroiliac Joint Pain: - Bimodal prevalence: younger individuals (often post-trauma, extraarticular) and older individuals (often intraarticular)
3. ETIOLOGY & PATHOPHYSIOLOGY¶
The etiologies of LBP can be broadly categorized into nociceptive (mechanical) causes, radicular causes, and nociplastic (central sensitization) causes.
3.1 Nociceptive Pain Sources¶
Myofascial Pain: - Muscles, ligaments, and fascia contain nociceptors and comprise large surface area within spinal structures - Studies show higher levels of neuropeptides (substance P, bradykinin), neurotransmitters (norepinephrine, 5-HT), and inflammatory cytokines (TNF- α , interleukins) in active trigger points - Lower pH levels and more vascular abnormalities in active vs latent trigger points - Higher myoelectric tone in patients with back pain compared to controls Discogenic Pain: - Accounts for 26-42% of axial LBP patients - In healthy disks, nerve fibers limited to outer annulus; in degeneration, they populate inner annulus and even nucleus pulposus - Associated with upregulation of inflammatory cytokines and hypermobility - Tearing and degeneration of annular fibers increases stress on intact annular rings and facilitates contact between intradiscal cytokines and sensitized nerve endings - Clinical presentation: pain worsened with sitting or bending forward, more likely bilateral, frequently radiates into upper/lower leg in nondermatomal distribution Facet Joint Pain: - May arise from synovial lining, fibrous capsule, and bone (all innervated with nociceptors) - Disk degeneration generally precedes facet degeneration and increases loadbearing - Presentation: unilateral paraspinal pain and tenderness (though advanced disease usually bilateral), morning stiffness, sitting may alleviate symptoms Sacroiliac (SI) Joint Pain: - May be extraarticular (ligaments) or intraarticular (bony structures, capsule, synovial lining) - SI joint: upper third is syndesmosis, lower two-thirds lined by synovium, lower third contains anteriorly situated joint capsule - Equal prevalence between extraarticular and intraarticular pathology - Extraarticular more common in younger individuals, after trauma, with prominent tenderness - Presentation: more likely unilateral than discogenic/facetogenic pain, most marked inferior to L5, about half have nondermatomal leg radiation, ~25% have radiation below knee, may radiate into groin
3.2 Radicular Pain Sources¶
Herniated Disk: - Patients present with LBP radiating into lower leg following dermatomal distribution (significant overlap/variability; up to 40% have multilevel involvement) - Frequently report sensory deficits - Neurologic motor deficits: 25-30% - Asymmetrical or diminished reflexes (<20%), most pronounced with L4 or S1 involvement Spinal Stenosis: - May be central (<10 mm anteroposterior diameter) or involve lateral recesses or foramina (<3 mm) - Anatomic etiologies: bulging/herniated disks, facet joint hypertrophy, spondylolisthesis, ligamentum flavum buckling/hypertrophy - Neurogenic claudication (sensitivity 88%, 95% CI 78-98%): back pain radiating into legs, exacerbated by activity, improved by rest (especially sitting) - Leaning forward (shopping cart sign) alleviates symptoms - Other signs: wide-based gait, poor balance, pain worsened by lumbar extension, diminished vibratory perception
3.3 Disk Degeneration Pathophysiology¶
In healthy intervertebral disks: - Notochord cells present (decrease as disks mature) - Intact annulus fibrosus In degenerated intervertebral disks: - Extension of nucleus pulposus into degenerated annulus fibrosus with inflammation - Neovascularization and nerve ingrowth - Bulging disk - Inflammatory cytokines (increase in number with disk degeneration) - Osteophyte formation - Endplate fractures
4. CLINICAL FEATURES¶
Clinical presentation varies based on the underlying etiology and pain mechanism involved.
4.1 Natural Course - Mechanical LBP¶
The distinction between acute (<3 months) and chronic LBP is crucial for prognosis. Acute Nonradicular Pain (systematic review of 11 studies): - 1 month: 80% still have pain (95% CI, 61-100%) - 3 months: 67% still have pain (95% CI, 50-83%) - 6 months: 57% still have pain (95% CI, 46-68%) - 12 months: 65% still have pain (95% CI, 54-75%) Chronic LBP: - Stagnant rates of improvement - Few patients improve dramatically after 6 months - Small percentage worsens
4.2 Natural Course - Radicular LBP¶
Radicular Pain: - 15-40% experience persistent symptoms at 6 months to 1 year - Herniated disks typically resorb within 2 years but often reherniate Spinal Stenosis: - Most patients remain stable - Small percentage progress - Unlike disk herniations, underlying pathology does not recede Risk Factors for Pain Persistence and Poor Outcomes: - Greater disease burden - Older age - Psychopathology - Poor job satisfaction - Secondary gain
4.3 Clinical Presentation by Etiology¶
Myofascial Pain: - Focal or diffuse tenderness (occasionally discrete trigger points) - Limited range of motion - Increased muscle tension - Functional scoliosis in severe cases - Normal neurologic exam Discogenic Pain: - Worsened with sitting or bending forward - More likely bilateral than facet or SI joint pain - Frequently radiates into upper and sometimes lower leg in nondermatomal distribution Facet Joint Pain: - Unilateral paraspinal pain and tenderness (bilateral in advanced disease) - Morning stiffness - Sitting may alleviate symptoms SI Joint Pain: - Tenderness below L5 - More likely unilateral - About half have nondermatomal leg radiation - ~25% have radiation below knee - May radiate into groin Herniated Disk: - Radicular pain following dermatomal distribution - Sensory deficits common - Motor deficits in 25-30% - Diminished reflexes (<20%) Spinal Stenosis: - Neurogenic claudication - Wide-based gait - Poor balance - Pain worsened by extension, improved by forward flexion
5. DIFFERENTIAL DIAGNOSIS¶
The differential diagnosis of LBP includes mechanical, radicular, neuropathic, nociplastic, and systemic causes.
5.1 Mechanical Causes¶
- Myofascial pain - Discogenic pain (intervertebral disk degeneration) - Facet joint arthropathy - Sacroiliac joint dysfunction (intraarticular or extraarticular) - Vertebrogenic pain (compression fractures, endplate inflammation) - Spondylolysis/spondylolisthesis
5.2 Radicular Causes¶
- Herniated disk - Spinal stenosis (central, lateral recess, foraminal) - Neuropathy (herpes zoster, diabetic amyotrophy)
5.3 Nociplastic Causes¶
- Nonspecific back pain - Central sensitization - Fibromyalgia
5.4 Systemic/Red Flag Conditions¶
- Infection (diskitis, osteomyelitis, epidural abscess) - Malignancy (primary or metastatic) - Inflammatory arthritis (ankylosing spondylitis, psoriatic arthritis) - Vascular (aortic aneurysm) - Cauda equina syndrome - Visceral pathology (pelvic/retroperitoneal organs)
6. INVESTIGATIONS & DIAGNOSIS¶
Diagnosis of LBP relies on a combination of thorough history, physical examination, and judicious use of imaging and ancillary tests.
Table 18-2: Summary of Common Physical Exam Maneuvers for the Low Back¶
| Test | Description | Comments |
|---|---|---|
| LUMBAR RADICULOPATHY | ||
| Straight Leg Raising (SLR) | Patient supine; examiner passively flexes leg at hip, reproducing radicular pain | Sensitivity 80% for L5 or S1; decreases for cephalad nerve roots; unreliable for spinal stenosis |
| Crossed SLR | Patient supine; examiner passively flexes contralateral leg, reproducing radicular pain in affected leg | High specificity (>85%) but low sensitivity |
| Femoral Stretch | Patient prone; examiner passively extends leg at hip, reproducing radicular pain in thigh | Modest sensitivity (50%) for L2-L4 nerve root impingement |
| SI JOINT PROVOCATION | ||
| Compression | Patient lateral decubitus with affected side up; examiner exerts downward pressure on superior iliac crest | No tests reliably distinguish intraarticular from extraarticular pathology |
| Thigh Thrust (POSH) | Patient supine; examiner flexes hip to 90°, flexes ipsilateral knee, applies downward pressure along femur axis | Sensitivity up to 50-80% |
| Distraction (Gapping Test) | Patient supine; examiner applies dorsolateral pressure on ipsilateral ASIS | Specificity up to 70-80% |
| FABER (Patrick's Test) | Patient supine; hip/knee flexed, foot under contralateral knee; downward pressure on knee | Battery of ‡3 tests: sensitivity ‡90%, specificity ‡80% |
| Gaenslen's Test | Patient supine at edge of table; hyperextend affected leg while maximally flexing contralateral hip/knee | Sensitivity up to 50-80% |
| Standing Hip Flexion Test | Patient stands and lifts one leg; examiner observes spine/pelvis from behind | Paradoxical or asymmetrical PSIS motion suggests SI joint mobility dysfunction |
| DEEP GLUTEAL/PIRIFORMIS SYNDROME | ||
| Freiberg's Sign | Patient supine; examiner passively extends, adducts, internally rotates thigh ("log roll") | Assesses sciatic nerve impingement by piriformis/gluteal muscles |
| Test | Description | Comments |
|---|---|---|
| FADIR (FAIR Test) | Patient supine; flex hip/knee, maximally adduct thigh, internally rotate hip | Stretches piriformis muscle |
| Pace Test | Patient sitting; abduct and externally rotate hip, eliciting pain | Variants exist with patient supine |
| Beatty Test | Patient lateral decubitus with affected side up; elevating leg elicits buttock pain | Causes piriformis contraction |
| SPONDYLOARTHROPATHY | ||
| Schober Test | Mark L5 and 10 cm superior; patient bends forward; <5 cm increase = positive | Nonspecific for inflammatory spinal arthritis |
| NONORGANIC SIGNS | ||
| Hoover's Sign | Patient supine; flex affected leg against resistance; unaffected leg should push down | Discordant response suggests malingering or functional disorder |
| Tripod Sign | Patient seated; elevating affected leg causes pain; leaning back should reduce pain | Failure to lean back suggests nonorganic pathology |
| Waddell Signs | 5 categories: nonanatomic tenderness, sham stimulation pain, distraction, regional disturbances, overreaction | Greater positive signs = greater risk of treatment failure |
Table 18-4: Red Flag Symptoms and Corresponding Pathology¶
| Finding | Potential Pathology |
|---|---|
| DEMOGRAPHICS | |
| Age £18 years | Congenital defect, tumor, spondylolysis, or spondylolisthesis |
| Age >50 years | Tumor, fracture, vascular abnormality (aortic aneurysm) |
| SOCIAL AND TREATMENT RELATED | |
| Intravenous drug use | Infection |
| Anticoagulant use | Hematoma |
| Recent procedure | Hematoma (complication) or infection |
| Immunocompromised state | Infection |
| Trauma | Fracture, hematoma |
| History of cancer | Tumor |
| SYMPTOMS | |
| Fever, night sweats, chills | Infection, tumor |
| Weight loss | Tumor, infection |
| Saddle anesthesia | Cauda equina syndrome |
| Urinary or rectal incontinence, sexual dysfunction | Cauda equina syndrome |
| Rapidly progressive or severe neurologic symptoms | Cauda equina syndrome |
| Pain not relieved by rest or at night | Tumor, infection |
| Finding | Potential Pathology |
|---|---|
| PHYSICAL EXAM SIGNS | |
| Saddle anesthesia | Cauda equina syndrome |
| Decreased rectal tone | Cauda equina syndrome |
6.1 History and Physical Examination¶
History and physical examination may identify patients requiring further workup and those with indications for advanced therapies but are rarely pathognomonic. Inspection: - Birthmarks and doughy lipomas can indicate spina bifida - Unusual patch of hair over spine may indicate bony pathology Gait Observation: - Propulsive gait: Parkinson's disease or antipsychotic drug use - Spastic gait: Central lesion - Waddling gait: Muscular dystrophy, spinal/gluteal muscle weakness, hip pathology - Steppage gait/foot drop: Peroneal neuropathy, large herniated disk, Guillain-Barré syndrome, multiple sclerosis Palpation: - Paraspinal tenderness with "fullness" or increased muscle tension: Muscle spasm or tear - Midline tenderness: Ligamentous injury Spine Alignment: - Scoliosis (sideways curvature): Predisposes to disk and facet joint degeneration - Functional scoliosis or decreased lordosis: Muscle spasm or postural dysfunction - Exaggerated lordosis: Tethered spinal cord or abdominal muscle weakness Range of Motion: - Decreased extension: Spinal stenosis or spondylolisthesis - Diminished forward flexion: Discogenic pain - Pain with transitional movements: SI joint pain Leg Length Discrepancy: - 20% have clinically relevant leg length discrepancy >9 mm - May predispose to SI joint pain, accelerated disk/facet degeneration, myofascial strain
6.2 Physical Examination Maneuvers¶
For Detecting Herniated Disk: - Straight leg raising (SLR): Sensitivity ~80% for L5 and S1 nerve roots; sensitivity decreases for cephalad nerve roots - Crossed SLR: High specificity (>85%) but low sensitivity - Femoral stretch test: Sensitivity >50% for mid-lumbar (L2-L4) nerve root involvement For Spinal Stenosis: - Older age - Positive treadmill test (decreased ambulatory capacity with increased inclination) - Positive Romberg's test - Pain that disappears with sitting - Perineal numbness For Discogenic Pain: - Centralization of pain with repeated movements - Pain worse with sitting - Midline tenderness For Facet Joint Pain: - Paraspinal tenderness (weakly associated) For SI Joint Pain: - Battery of ≥ 3 positive provocative tests (sensitivity potentially ≥ 90%, specificity potentially ≥ 80%) - Pain below L5 - Radiation into groin Neurologic Exam: - Patellar reflex: L4 (and sometimes L2/L3) - Achilles reflex: S1 - ~5% of younger individuals have absent reflexes - >1/3 of older individuals have absent reflexes - ~25% of people have asymmetrical reflexes For Cauda Equina Syndrome: - Perianal sensation assessment - Rectal exam for sphincter tone
6.3 Imaging¶
General Principles: - Advanced imaging lacks specificity; most studies show no significant correlation between imaging and symptoms - High percentage of abnormalities found in populations without back pain - Treatment decisions should rarely be predicated on imaging findings alone Indications for Imaging: - Acute LBP with red flags or serious/progressive neurologic deficits - Chronic LBP: MRI on case-by-case basis, especially when considering invasive interventions Imaging Modalities: - MRI: Gold standard for detecting soft tissue abnormalities including herniation; can reveal active inflammation; needed to determine acuity/chronicity of fractures - CT: Better spatial contrast; more sensitive for some bone abnormalities; sensitivity >90% for most lumbar pathology including disk herniations - Plain Films: Useful for scoliosis, spondylolisthesis, fractures (including pars interarticularis) Note: A randomized trial failed to demonstrate that MRI improved outcomes or meaningfully affected decision-making for lumbar epidural steroid injections.
6.4 Electrodiagnostic Testing¶
Electromyography (EMG) and nerve conduction studies are used to identify peripheral sources of nerve and muscle injury. Indications: - Multiple dermatomal involvement or atypical extremity pain - Conflicting symptoms and imaging findings - Transitional anatomy or aberrant innervation Transitional Anatomy: - "Lumbarization" of S1 (sixth vertebral body present) - "Sacralization" of L5 (partial/complete anatomic fusion of L5 with S1) - Present in 15-35% of population - Associated with increased prevalence of back pain Test Characteristics: - Sensitivity for radicular pain without focal neurologic findings: 36-64% - Sensitivity with abnormal neurologic examination: 51-86% - Specificity: 50-60%
6.5 Selective Nerve Root Blocks¶
SNRBs can identify a symptomatic nerve root in ambiguous cases. Technique: - Similar to transforaminal ESIs but involves blockade of only a single nerve root - High-volume injections (>0.5 mL) undermine specificity Evidence: - No randomized studies evaluating effect on postsurgical decompression outcomes - Retrospective studies show modest correlation between pain relief after SNRB and surgery - Systematic review: 93% sensitivity, 26% specificity (very low-quality studies) - Addition of SNRB to routine presurgical workup is not cost-effective
6.6 Diagnostic Blocks and Discography¶
Facet Joint Pain: - Diagnosed via anesthetic blocks of medial branches innervating the joints or the joints themselves - Subject to high false-positive rates SI Joint Pain: - Reference standard: Low-volume anesthetic blocks - Physical exam: Battery of ≥ 3 positive provocative tests has high sensitivity and specificity for intraarticular SI joint pain Discogenic Pain: - Provocative and analgesic discography sometimes used - High false-positive rates in some populations (psychiatric morbidities, somatization, multiple other pain conditions)
7. MANAGEMENT & TREATMENT¶
Contemporary strategies for managing acute and chronic LBP prioritize optimization of nonpharmacologic modalities with graded, patient-centered incorporation of pharmacologic, interventional, and surgical treatments.
Table 18-3: Clinical Evaluation, Diagnosis, and Treatment of Low Back Pain Etiologies (Summary)¶
| Etiology | Risk Factors | Clinical Presentation | Diagnosis | Treatment |
|---|---|---|---|---|
| Myofascial Pain | Strenuous activities, sedentary lifestyle, abrupt movements | Axial pain, occasionally referred to thigh/mid-back/groin; focal or diffuse tenderness; trigger points | Ultrasound or EMG occasionally | NSAIDs, nonbenzodiazepine muscle relaxants, antidepressants; topical analgesics; trigger point injections |
| Etiology | Risk Factors | Clinical Presentation | Diagnosis | Treatment |
|---|---|---|---|---|
| Discogenic Pain | Advanced age, genetic predisposition, repetitive trauma | Axial pain worse with sitting/forward flexion; bilateral more than facet/SI joint pain; radiation to extremities | MRI; discography (high false-positive rate) | NSAIDs, antidepressants, topical analgesics; IDET or biacuplasty; ESI or intradiscal corticosteroids (mixed efficacy) |
| Vertebrogenic Pain | Advanced age, osteoporosis, trauma | Axial pain worsened with activities; may radiate to upper leg | MRI for endplate abnormalities; plain films for acute fractures | NSAIDs, antidepressants, topical analgesics; judicious opioids for severe acute pain; vertebral augmentation; basivertebral nerve RFA |
| Facet Joint Pain | Increasing age, repetitive strain, genetic predisposition | Axial pain may radiate to lower legs; paraspinal tenderness; improved with sitting | MRI or CT; diagnostic medial branch or intraarticular injections | NSAIDs, antidepressants; RFA of medial branch nerves after positive diagnostic block |
| SI Joint Pain | Bimodal (younger post-trauma; older with degeneration); hip pathology, inflammatory arthritis, lumbar spine surgery | Unilateral or bilateral pain; tenderness below L5; ~50% have leg radiation; may radiate to groin | CT (especially for extraarticular); battery of ‡3 provocative tests; diagnostic injection | NSAIDs, antidepressants, topical analgesics; intraarticular or extraarticular SI joint injection; RFA of sacral lateral branch nerves; minimally invasive fusion |
| Herniated Disk | Peak prevalence 30-50 years; disk degeneration, trauma, genetic predisposition, heavy lifting, obesity, smoking | Axial and radicular pain in dermatomal distribution; sensory/motor loss; diminished reflexes; positive SLR | MRI or CT scan, myelography; electrodiagnostic tests; selective nerve root blocks | NSAIDs, muscle relaxants, antidepressants; gabapentinoids (minimal benefit); ESIs (most effective in acute phase); surgical decompression for severe/progressive deficits |
| Spinal Stenosis | Advanced age, concomitant spinal pathology | Usually bilateral radicular pain; neurogenic claudication; wide-based gait; improved with forward flexion | MRI or CT scan | NSAIDs, muscle relaxants, antidepressants; gabapentinoids; ESIs (short- to intermediate-term benefit); surgical decompression for progressive pathology |
| Etiology | Risk Factors | Clinical Presentation | Diagnosis | Treatment |
|---|---|---|---|---|
| Central Sensitization (Nonspecific Back Pain) | Peak age 20s-50s; more common in females; genetic predisposition | Bilateral pain involving multiple regions; diffuse tenderness; high co-prevalence with other nociplastic conditions; high mood disorder rate | Clinical presentation; Central Sensitization Inventory; painDETECT; conditioned pain modulation | NSAIDs, muscle relaxants, antidepressants, gabapentinoids, OTC topical analgesics; nonpharmacologic therapies (exercise, targeted therapy) should be prioritized |
7.1 General Principles¶
Biopsychosocial Model: Recognizes that psychological (e.g., underlying mood disorders) and social factors (e.g., systemic barriers to care) contribute to overall perception and experience of pain. Interdisciplinary Approach: Team involving specialists from pain medicine, orthopedic/neurosurgical spine surgery, physical therapy, and psychology/psychiatry provides better improvements in pain, function, and quality of life. Restrictions in coverage from health care payors have hindered widespread implementation. Acute LBP: - Most cases resolve within 6 weeks - Over-the-counter analgesics plus nonpharmacologic treatments (targeted physical therapy, core-strengthening exercises, education) frequently suffice without imaging or prescription analgesics
7.2 Pharmacotherapy¶
Around 25% of patients with acute LBP develop chronic symptoms ( ≥ 3 months). First-Line Options: - NSAIDs - Nonbenzodiazepine muscle relaxants - Antidepressants (duloxetine [SNRI], tricyclic antidepressants) NOT Recommended: - Acetaminophen: Unlikely to provide significant analgesia; no longer recommended as first-line agent - Gabapentinoids (gabapentin, pregabalin): Insufficient evidence for axial or radicular back pain Opioids: - Have not demonstrated significant long-term benefits for analgesia or function - May be considered on case-by-case basis for debilitating acute pain or severe chronic LBP exacerbations - Associated with serious potential harms: respiratory depression, addiction, endocrinologic disturbances - If used: lowest effective dose, shortest duration feasible, clearly defined treatment goals - Avoid concomitant use with benzodiazepines (increased respiratory depression risk)
7.3 Psychological Therapies¶
Co-prevalence of Psychopathology with Chronic Back Pain: - Depression: 33-67% - Anxiety: 10-30% - Substance misuse disorders: 13-40% - Axis II disorders (personality disorders): >50% in some studies - Lifetime co-prevalence of axis I and II conditions is even higher Beneficial Psychological Therapies: - Targeted education - Mindfulness-based stress reduction - Operant therapy - Biofeedback - Progressive relaxation - Cognitive-behavioral therapy Evidence: - Greatest for patients with chronic pain - No individual therapy demonstrates consistent superiority - Stronger evidence for short-term than long-term benefit - Benefits wane without ongoing follow-up
7.4 Physical Therapies¶
Physical therapists evaluate and educate patients regarding kinesiologic/functional abnormalities, provide procedural interventions, develop exercise regimens, and provide treatments (hot/cold packs, manual therapies, massage, neuromuscular reeducation). Exercise: - Shown to reduce pain and increase function for radicular and nonradicular back pain - Effects diminish over time if exercises cease - Most studies fail to demonstrate one type as more beneficial than another - Yoga and Tai Chi are commonly studied therapies Acute Back Pain: - Early resumption of activities including exercise (within 2 weeks) is widely recommended - Studies are mixed regarding long-term effect on pain and function
7.5 Integrative Medicine¶
Massage: - May benefit individuals with acute and chronic pain with prominent soft tissue symptoms (spasmodic or tension-based pain) - Analgesic benefits tend to be short-lived Spinal Manipulation: - May provide small benefits for acute and chronic back pain and physical function vs absence of therapy - Effects diminish over time - Noninferior to other recommended physical therapies - Mixed evidence for benefit vs sham or as add-on treatment Acupuncture: - Effective for pain and (to lesser degree) secondary outcomes in acute and chronic LBP - Effects tend to be modest and short-lived without continued therapy - Similar effects for various types (electroacupuncture, moxibustion, auricular, cupping) - True acupuncture slightly more effective than sham acupuncture - Sham acupuncture more effective than no treatment (likely placebo effect) Note: No evidence supports one form of integrative treatment over others.
7.6 Interventional Procedures for Axial LBP¶
Lumbar Medial Branch Nerve Blocks and Ablation (Facet Joint Pain): - Diagnosis established through diagnostic medial branch blocks (local anesthetic onto nerves innervating facet joints) - If significant improvement in pain and function, diagnosis confirmed - Same nerves can be ablated via radiofrequency ablation (RFA) SI Joint Interventions: - SI joints confirmed as primary etiology in 20-35% of suspected lower axial LBP - Low-volume intraarticular SI joint injection is reference standard for diagnosis - Treatments differ based on pathology type: - Intraarticular: Minimally invasive fusion for refractory cases or joint malalignment - Extraarticular: RFA of sacral lateral branch nerves if intraarticular injections provide only transient relief Intradiscal Interventions (Discogenic Pain): - Discography: High false-positive rates in certain populations; associated with accelerated disk degeneration - IDET or biacuplasty: May be considered for non-fragmented disks without extrusion; mixed evidence for intermediate-term benefit - Intradiscal corticosteroids or ESIs: Mixed efficacy for short-term benefit - Bone marrow concentrate: Emerging study topic; 2019 FDA warning about stem cell therapies Trigger Point Injections (Myofascial Pain): - Relieve spasmodic activity by improving local blood flow via vasodilation - Facilitate removal of inflammatory mediators and cytokines - No superiority of any specific injectate (saline, local anesthetic ± steroids, botulinum toxin) - Mechanism of action independent of medications administered Vertebral Augmentation (Vertebrogenic Pain): - Most vertebral compression fractures improve within 6-8 weeks of conservative therapy; up to 40% may result in chronic pain - <10% of posterior lumbar compression fractures associated with nerve root impingement or spinal cord injury - Vertebroplasty or kyphoplasty can be considered for severe pain/disability due to acute (<6 weeks) compression fracture - May work by stabilizing fracture and denervating nociceptive fibers Basivertebral Nerve Ablation (Vertebrogenic Pain): - For patients with Modic type 1 or type 2 changes on MRI in whom other spine structures are less likely to be the predominant pain source - RFA of basivertebral nerves innervating vertebral endplates can be considered
7.7 Interventional Procedures for Radicular LBP¶
Epidural Steroid Injections (ESIs): - Most patients with acute radicular pain from herniated disk improve within 3 months with conservative management - Natural history of spinal stenosis is more guarded (causes often progress with age) - Over two-thirds of herniated disks retract within 2 years - Most studies fail to show differences in response rates between stenosis and herniated disks - Poorer response rate for noncompressive (e.g., degenerative disks causing chemical irritation) pathologies - Evidence for weak but potentially meaningful surgery-sparing effect for radicular pain
7.8 Surgical Management¶
Lumbar surgeries can be broadly categorized as fusion, decompression (diskectomy or laminectomy), or combination. Lumbar Interbody Fusion: - Commonly performed for spinal instability (symptomatic/severe spondylolisthesis) or severe axial pain refractory to nonsurgical management with severe functional disability - Precise indications remain controversial - Mixed data regarding effectiveness for axial back pain and disability - Strongest evidence for spondylolisthesis (often associated with instability) Disk Arthroplasty: - For single-level (sometimes two-level) discogenic pain without posterior element involvement - At least as effective as circumferential or anterior fusion for pain and function - Better preservation of motion - Quality of studies generally poor (most industry funded) - Adjacent segment disease can occur following both procedures but more likely after fusion - Risk of postsurgical instability greater following disk arthroplasty Lumbar Nerve Root Decompression: - Indicated for severe/progressive neurologic deficits or severe radicular pain refractory to interventional treatments, medications, and physical therapy - Role of fusion in addition to decompression is controversial - Studies show higher complication rates without greater benefit for nerve root compression without instability Spinal Stenosis: - Mixed results on whether surgical decompression is superior to conservative management - Meta-analyses: Small benefit that diminishes after 2 years - Minimally invasive options: Interspinal spacers, minimally invasive lumbar decompression Herniated Disk: - Randomized trials: Greater short-term reduction in pain and disability, but small/questionably meaningful benefits after 1 year - Minimally invasive options: Chemonucleolysis, endoscopic discectomy
7.9 Postlaminectomy Syndrome (Failed Back Surgery Syndrome)¶
Risk Factors: - Younger age - Female sex - Opioid use - Poor patient selection (irrelevant baseline conditions, greater presurgical disease burden) - Concurrent pain conditions - Central sensitization Clinical Features: - Often involves axial and radicular pain in multidermatomal fashion - Neurologic signs may be in multiple dermatomes - Sensory and motor loss, diminished reflexes common - Muscle loss/wasting, pseudoarthroses, retained disk fragments, lordosis may be appreciated - Epidural scar tissue, arachnoiditis common - Superficial tenderness and muscle wasting may present with nociplastic pain - Worsening pain with muscle wasting may present weeks or months after surgery - Adjacent segment disease can take >1 year to manifest Diagnosis: - MRI with gadolinium or myelography - Electrodiagnostic tests - Diagnostic blocks (discography, facet blocks) associated with high false-positive rate Treatment: - Pharmacologic: NSAIDs, nonbenzodiazepine muscle relaxants, antidepressants, gabapentinoids - Interventional: Epidural lysis of adhesions may be considered for epidural scar tissue; SCS may be considered in refractory cases especially when neuropathic symptoms predominate
8. PROGNOSIS & COMPLICATIONS¶
Prognosis varies significantly based on the acuity, etiology, and patient characteristics.
8.1 Prognosis by Type¶
Acute Nonradicular LBP: - 80% still have pain at 1 month - 65% still have pain at 12 months - ~25% develop chronic symptoms Chronic LBP: - Stagnant rates of improvement - Few patients improve dramatically after 6 months Radicular LBP (Herniated Disk): - 15-40% have persistent symptoms at 6-12 months - Disks typically resorb within 2 years but often reherniate Spinal Stenosis: - Most patients remain stable - Small percentage progress - Underlying pathology does not recede
8.2 Prognostic Factors¶
Risk Factors for Pain Persistence and Poor Outcomes: - Greater disease burden - Older age - Psychopathology - Poor job satisfaction - Secondary gain - Nonorganic signs (associated with treatment failure)
8.3 Surgical Complications¶
Postlaminectomy Syndrome: - Risk factors: Younger age, female sex, opioid use, poor patient selection, concurrent pain conditions, central sensitization - May involve epidural scar tissue, arachnoiditis, pseudoarthroses, retained disk fragments Adjacent Segment Disease: - Can occur following fusion or disk arthroplasty - More likely after fusion than arthroplasty - May take >1 year to manifest Complications of Discography: - High false-positive rates in certain populations - Associated with accelerated disk degeneration based on animal and clinical studies
9. SPECIAL CONSIDERATIONS¶
Various patient populations and conditions require specific attention in the evaluation and management of LBP.
9.1 Age-Related Considerations¶
Pediatric/Young Adults ( ≤ 18 years): - Red flag: Consider congenital defect, tumor, spondylolysis, or spondylolisthesis Older Adults (>50 years): - Red flag: Consider tumor, fracture, vascular abnormality (aortic aneurysm) - Higher prevalence of spinal stenosis, facet joint pain, vertebral compression fractures - >1/3 have absent reflexes on examination - Gabapentinoids should be used cautiously (dizziness, somnolence, gait disturbance)
9.2 Transitional Anatomy¶
- "Lumbarization" of S1 (sixth vertebral body present) - "Sacralization" of L5 (partial/complete anatomic fusion of L5 with S1) - Present in 15-35% of population - Associated with increased prevalence of back pain - May require electrodiagnostic testing to clarify anatomy
9.3 Psychiatric Comorbidities¶
High Co-prevalence with Chronic Back Pain: - Depression: 33-67% - Anxiety: 10-30% - Substance misuse disorders: 13-40% - Personality disorders: >50% in some studies - Fear avoidance, catastrophization, poor coping skills - Posttraumatic stress disorder - Somatic symptom disorder Clinical Implications: - Psychiatric conditions exist along a continuum - Many patients may benefit from precision psychotherapies despite not meeting formal diagnostic criteria - Identify and address underlying psychiatric and mood conditions - Nonorganic signs (Waddell signs) may signify underlying psychopathology and are associated with treatment failure
9.4 Special Populations Requiring Urgent Workup¶
Immunocompromised State: - Increased risk of infection IV Drug Users: - Increased risk of infection History of Cancer: - Consider metastatic disease Recent Spinal Procedure: - Consider hematoma or infection Trauma: - Consider fracture or hematoma Anticoagulant Use: - Increased risk of hematoma
10. KEY POINTS & CLINICAL PEARLS¶
Essential takeaways for clinical practice in the evaluation and management of low back pain.
10.1 Diagnostic Pearls¶
- History and physical examination guide diagnosis but are rarely pathognomonic - Over half of individuals may have mixed pain phenotypes - Radiculopathy can occur without pain, and radicular pain frequently occurs without neurologic deficits - Most studies demonstrate no significant correlation between imaging and symptoms - Treatment decisions should rarely be predicated on imaging findings alone - Battery of ≥ 3 positive SI joint provocative tests has high sensitivity ( ≥ 90%) and specificity ( ≥ 80%) - Straight leg raising test has 80% sensitivity for L5/S1 nerve roots; crossed SLR has >85% specificity - Discography has high false-positive rates in patients with psychiatric morbidities, somatization, or multiple pain conditions
10.2 Red Flag Recognition¶
- 92.6% of patients with LBP endorse at least one red flag - Most common red flag: Night pain (58.1%) - Presence of red flags can predict neurologic emergency, but absence does not meaningfully decrease likelihood - Cauda equina syndrome requires urgent MRI confirmation: saddle anesthesia, incontinence, decreased rectal tone - Age <18 years: Consider congenital defect, tumor, spondylolysis - Age >50 years: Consider tumor, fracture, aortic aneurysm
10.3 Treatment Principles¶
- Prioritize nonpharmacologic modalities with graded addition of pharmacologic and interventional treatments - Acetaminophen is no longer recommended as first-line for back pain - Opioids have not demonstrated significant long-term benefits; if used, lowest dose for shortest duration with defined goals - Avoid concomitant opioid-benzodiazepine use - Gabapentinoids have insufficient evidence for axial or radicular back pain
- Physical therapy should be cornerstone of treatment; effects diminish if exercises cease - Interdisciplinary treatment programs provide better outcomes but face coverage restrictions
10.4 Interventional Procedure Selection¶
- Facet joint pain (10-15% of axial LBP): Diagnostic medial branch blocks → RFA - SI joint pain (20-35% of lower axial LBP): Intraarticular injection is reference standard → RFA or fusion - Discogenic pain (26-42% of axial LBP): Evidence for IDET/biacuplasty is mixed - ESIs may be most effective in acute phase of radicular pain from disk herniation - ESIs show weak but potentially meaningful surgery-sparing effect
10.5 Surgical Decision-Making¶
- Strongest evidence for fusion is in spondylolisthesis - Decompression for herniated disk: Greater short-term benefit, small/questionable benefits after 1 year - Decompression for spinal stenosis: Small benefit that diminishes after 2 years - Adding fusion to decompression without instability shows higher complication rates without greater benefit - Adjacent segment disease more common after fusion than disk arthroplasty